id: 05135229
dt: j
an: 05135229
au: Phang Trung Huy; Nguyen Thi Thanh Huyen
ti: Generating of minimal unavoidable sets.
so: Vietnam J. Math. 34, No. 4, 459-472 (2006).
py: 2006
pu: Vietnamese Academy of Science and Technology, Hanoi; Vietnam Mathematical
    Society, Hanoi
la: EN
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ab: Summary: We investigate several transformations on unavoidable sets which
    preserve the minimality of such sets. The main result confirms that any
    minimal unavoidable set over an alphabet $A$ can be obtained from $A$,
    regarded as the initial minimal unavoidable set, by finitely many
    applications of such transformations. As a consequence, a procedure to
    generate all possible minimal unavoidable sets over $A$ is proposed.
    This allows us in particular to generate easily counter-examples for
    both Ehrenfeucht’s conjecture and Haussler’s one on unavoidable
    sets.
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